Comprehensive Immunogenomic Profiling of IDH1-/2-Altered Cholangiocarcinoma.

PURPOSE: Isocitrate dehydrogenase (IDH)1/2 genomic alterations (GA) occur in 20% of intrahepatic cholangiocarcinoma (iCCA); however, the immunogenomic landscape of IDH1-/2-mutated iCCA is largely unknown. METHODS: Comprehensive genomic profiling (CGP) was performed on 3,067 cases of advanced iCCA. Tumor mutational burden (TMB), PD-L1 expression (Dako 22C3), microsatellite instability (MSI), and genomic loss of heterozygosity (gLOH) as a surrogate marker for homologous recombination deficiency were examined. RNA sequencing of 73 patient samples was analyzed for differences in stromal/immune cell infiltration, immune marker expression, and T-cell inflammation. Tissue microarray arrays were subjected to multiplex immunohistochemistry and colocalization analysis in 100 surgical samples. Retrospective clinical data were collected for 501 patients with cholangiocarcinoma to examine median overall survival (mOS) in IDH1/2+ versus IDHwt. RESULTS: Of 3,067 iCCA cases subjected to CGP, 426 (14%) were IDH1+ and 125 (4%) were IDH2+. IDH1 GA included R132C (69%) and R132L/G/S/H/F (16%/7%/4%/3%/<1%). IDH2 GA occurred at R172 (94.4%) and R140 (6.6%). No significant difference was seen in median gLOH between IDH1+ versus IDHwt iCCA (P = .37), although patterns of comutations differed. MSI-High (P = .009), TMB ≥10 mut/Mb (P < .0001), and PD-L1 positivity were lower in IDH1/2+ versus IDHwt iCCA. Resting natural killer cell population, CD70, and programmed cell death 1 expression were significantly higher in non-IDH1-mutated cases, whereas V-set domain containing T-cell activation inhibitor 1 (B7-H4) expression was significantly higher in IDH1+. No significant difference in mOS was observed between IDH1/2+ versus IDHwt patients. CONCLUSION: Significant differences in GA and immune biomarkers are noted between IDH1/2+ and IDHwt iCCA. IDH1-/2-mutated tumors appear immunologically cold without gLOH. These immunogenomic data provide insight for precision targeting of iCCA with IDH alterations.

Comparative Genomic Analysis and Clinical Outcomes of BRAF-mutated Advanced Biliary Tract Cancers.

PURPOSE: BRAF mutations are rare in biliary tract cancers (BTC), but are of interest given the recent developments in targeted therapy for BTC. We investigated the clinical outcomes in a cohort of BRAF-mutant advanced BTC treated with first-line chemotherapy. Furthermore, we investigated the genomic landscape of BRAF class I, II, and III mutations in the intrahepatic cholangiocarcinoma (iCCA) subgroup of BTC. EXPERIMENTAL DESIGN: We analyzed two nonoverlapping cohorts. We examined the genomic landscape of BRAF-mutated iCCA in a "genomic cohort" [187 class I, 82 class II, 113 class III BRAF mutants and 8,026 wildtype (WT)]. We also analyzed median progression-free survival (PFS) and overall survival (OS) on first-line chemotherapy in a separate multi-institutional "clinical cohort" of patients with BTC (including iCCA and extrahepatic cholangiocarcinoma (eCCA) and gallbladder cancer; 41 class I, 32 class II+III BRAF mutants and 1,042 WT). RESULTS: In the entire BTC clinical cohort, the median PFS was shorter for class I [HR, 2.11 (P < 0.001)] and class II+III [HR, 1.72 (P = 0.007)] as compared with BRAF WT. OS was also shorter in class I [HR, 2.04 (P = 0.011)] and class II+III [HR, 1.86 (P = 0.002)] as compared with BRAF WT. In the iCCA subgroup, class I alterations were mutually exclusive with FGFR2, IDH1/2, ERBB2, and KRAS mutations. Class II+III mutations appear to be mutually exclusive with FGFR2 and KRAS. CONCLUSIONS: In BTC, all classes of BRAF mutations are associated with a worse prognosis. BRAF mutations occur in 5% of iCCA subgroup and may be mutually exclusive with other targetable mutations.

Phase II Study of Ramucirumab in Advanced Biliary Tract Cancer Previously Treated By Gemcitabine-Based Chemotherapy.

PURPOSE: VEGF receptor-2 (VEGFR-2)-mediated angiogenesis contributes to pathogenesis of biliary tract cancers (BTC). We investigated ramucirumab, a mAb targeting VEGFR-2 for treatment of advanced, chemorefractory BTC. PATIENTS AND METHODS: This is a phase II, single-arm trial for advanced, unresectable, pre-treated patients with BTC with ECOG 0/1, adequate liver, renal, and marrow functions. Ramucirumab was administered at 8 mg/kg, 2 weekly with restaging performed 8 weekly. Primary endpoint was progression-free survival (PFS). Secondary endpoints were overall response rate (ORR), disease control rate (DCR), overall survival (OS), and toxicity. Exploratory endpoints included correlation of tumor mutational status with PFS and OS. RESULTS: 61 patients were enrolled: the median age was 58.5 years; 59 with stage IV disease; 62%, intrahepatic cholangiocarcinoma; 22%, gallbladder cancer; and 16%, extrahepatic cholangiocarcinoma. All received prior chemotherapy: 52% had 1 prior, and rest ≥2 prior lines. Median treatment duration was 10.1 weeks (range, 2.1-86). Median PFS was 3.2 months [95% confidence interval (CI), 2.1-4.8]; median OS, 9.5 months (95% CI, 5.8-13.6). One (1.7%) patient achieved partial response; 26 (43.3%), stable disease; and 25 (41.7%), disease progression; DCR, 45%. Median 6-month PFS and OS rates were 32% (95% CI, 0.22-0.46) and 58% (95% CI, 0.47-0.72). The majority of toxicities were grade 1 or 2; grade 3 proteinuria (1, 2%), hypertension (13, 22%), and pulmonary embolism (1, 2%), and grade 4 gastrointestinal bleeding (1, 2%) occurred. CONCLUSIONS: Ramucirumab was well tolerated and resulted in PFS similar to that achieved with other chemotherapy regimens used historically for chemorefractory BTC.